Antarctica, Macabre and Sublime (more pics on Picasa.)

And here’s today’s post: MYSTERY

This time we actually saw a Weddell seal! First wildlife we’ve seen in person yet. Perhaps we’ll manage a penguin next. The seal was hauled out on the ice near our study site–an unusual thing this time of year, because of the cold. It was a good twenty or thirty degrees (Celsius) colder above the ice than in the water beneath it, so I imagine that emerging from a hole in the ice and hauling out into the chilly air was rather like leaving a warm bath and running right out into a brisk and breezy fall evening.

The seal, visible in the distance behind Steve.

There’s another study group here looking for Weddell seals, so we gave them a call on our radio and they rushed out to take a look. They have the proper permits to be able to approach Antarctic wildlife, and they walked out alongside the seal and determined that it was a yearling male, too small for their purposes. They’re attaching instruments to the seals–cameras and other things that will give them information about the seals’ hunting behavior–so they need an adult-sized seal for things to work properly. They told us that the seal had probably been driven out of a breathing hole by larger males; breathing holes are a scarce resource, and I guess a yearling seal just doesn’t have the oomph to compete with half-ton adults.

The seal, galumphing (I'm told that's the technical term for the inchwormish way seals get across the ice.)

Scientifically, the day was interesting; we experimented with creating new sea ice by pouring out jugs of seawater onto a surface we’d shoveled clean. The surface wasn’t ideal, but we did discover that we could see a very distinct brightening of the new surface ice when it reached the temperature where the salt crystallized in the brine pockets.

The analytic spectrometer. Just before sunset the sun dipped below the cloud cover, turning our nice diffuse light into a direct beam, so we had to stop taking measurements until it set.

We got back just a couple of hours before a rather nice storm hit the station, with so much snow blowing that you could barely see a building across the street. It was fun in town, but I’m certainly glad we didn’t have to drive back in it.

Another day out on the ice tomorrow–more exploration this time, if the weather is appropriate (that is to say, cloudy but not too stormy.)

Steve Warren is the Principal Investigator of the project, a professor at University of Washington, and my advisor (my advisor for astrobiology-related projects, that is; my advisor for glaciology projects is Ed Waddington.) He’s been down to the Ice more times than I can keep track of, he knows an immense amount about light and radiation and how it relates to climate, and he keeps his eyes open for interesting problems to solve.

Rich Brandt is a research scientist at University of Washington, though he telecommutes in from upstate New York. He is an expert on ice, snow and the reflection of light therefrom. He too has lots of on-Ice experience. He uses his excellent camera skills and vast collection of equipment to record Antarctic vistas and small stuffed penguins alike.

These are the individuals with whom I am privileged to work, who have developed most of the research protocols we’re following as we do science on this trip. They will show up in my pictures a lot.

Some nice sastrugi (snow dunes) with a band of mirage in the background

A mysterious cyclopean edifice in the distance

We returned to our previous sample spot and attempted to get better measurements by removing the snow:

Janitorial duty on the sea ice

The crust of snow was pretty well stuck on to the ice, requiring us to shovel, sweep, and then kneel down and scrape with spatulas and ice axes until the ice was more or less clear. We tasted the snow and found it was salty, which means that a lot of it actually started out as frost flowers. Frost flowers are fluffy, rather ethereal-looking crystals that form on new sea ice; they are pretty fascinating, scientifically. If anyone requests it in the comments I’ll write up a post about how they form.

Nifty as frost flowers are, they are making our life difficult. As you may recall from my previous post Salt, Sea Ice and Science we are looking at the way the albedo of sea ice changes when the salt in brine pockets forms crystals. Unfortunately, it’s very hard to see anything useful through a layer of frost flower remains. Hence our janitorial activities.

I am reminded that I promised equipment pictures in that post I just linked. You’ve seen the field equipment, of course, but I shall have to do a post about lab technique and some pictures of my impressive array of beakers.

We had a lot of this out in the field today. My issues with spectacles persist (frosting over completely, attempting to freeze to my face, what have you) and the goggles do nothing don’t help very much. (The little fan died their first day out, as I sort of expected it to do.) Our ice corer nearly got stuck in the ice. And our electronic thermometer, which we use to take the temperature of ice cores, refuses to function properly when it gets too cold. This meant I spent quite a while with it stuck down the front of my pants, nestled against my belly, trying to get it warm enough to give a reading–like an emperor penguin incubating an egg, as my advisor put it.

Speaking of penguins, I saw my first sign of the local wildlife today. Small clouds of steam, puffing up from a crack in the sea ice once a second or so: a Weddell seal at a breathing hole. We didn’t see the actual seal, of course. Weddell seals are fascinating creatures. They live under the sea ice, so they have to breathe through any cracks or holes in the ice they can find. They keep them open by chewing away at the ice as the holes freeze over. Any hole in the ice is likely to attract a Weddell seal; Antarctic divers often find themselves suddenly sharing their diving hole with a half-ton of blubbery, snorting Weddell, and our Kiwi friends say that their little hut on the sea ice has been visited (and splattered with seal snot) more than once.

A Weddell seal breathing hole in a sea ice crack.

It seems like a precarious lifestyle, being dependent upon the ever-shifting sea ice just to be able to breathe. Antarctic animals are a resilient and determined lot.

The ride out was as bumpy as before, except this time we had the Analytic Spectral Device (for measuring albedos) along and thus had to be extra careful about excessive vibration.

We were looking for first-year sea ice that was bare of snow. We ended up near Tent Island, where our Kiwi friends had told us we might be able to find something sufficiently wind-scoured. No bare ice was immediately apparent, but we did find this iceberg trapped in the sea ice:

Click for larger version.

Say 'freeze'!

We investigated it, being careful to stay well clear of any possible falling ice. Icebergs are not to be trifled with; you can see the size of this one, and imagine how even a smallish piece of it might feel if it were to detach while you were underneath it.

Having found no bare ice even in the most wind-scoured of spots, and with the sun gradually sinking towards the horizon, we retraced our steps to an area which at least didn’t have very much snow and broke out our gear.

Rich uses the ASD to measure light levels. An overcast day is best for this, because the light comes in more evenly from all directions.

Me and the ice-coring device. Wrestling one of these down into the ice warms you up rather nicely, even at temperatures in the -30 range.

The snow was not very deep at all, but unfortunately even not-very-deep snow has quite a significant effect on albedo.

We got our albedo measurements, and we got our ice core, and we got very cold indeed.

On the way back we stopped in the sea ice hut the Kiwis have been using all winter, where they graciously fed us tea and cake. They also showed us their conductivity/temperature/depth sensor and the nifty hole in the sea ice–conveniently located within the warm confines of the hut–through which they lower it to get profiles of the ocean water below. Afterwards they kindly directed us to their own road back towards base, which felt orders of magnitude smoother than the route we’d been using and allowed us to get home in one hour instead of three despite being technically longer. An excellent day all round.

Being out on the ice is a strange experience. Here at McMurdo, you can pretend you’re just in some small town in Alaska. Out on the ice, though, the vast expanse of frozen water stretches out around you and the landscape is considerably more alien. I still find it slightly unnerving to drive across the sea ice, despite the fact that it is demonstrably strong enough (at this time of year) to land enormous planes on and has no trouble with our little pisten bully.

On Monday we went out on a scouting trip to see what the terrain was like around the places we wanted to go. It turned out to be a very long commute, mostly due to the very uneven surface. Sea ice that has been around for a few seasons (which we call multi-year sea ice) collects hummocks of windblown snow called sastrugi. You can see a few in the foreground of this picture. They are usually of a concrete-like hardness, and since a pisten bully has no suspension aside from the spring-mounted driver’s seat, you have to go over them quite slowly to avoid shaking yourself and your equipment to bits.

We did see some interesting wind effects. In this picture, you can see the snow blowing over the ice on the right-hand side; on the left-hand side the wind is blocked by our parked pisten bully. In the middle Rich is conveniently blotting out the setting sun so that I can take the photo. (I need to do a proper introduction post for Steve, my advisor and the head of the project, and Rich, our collaborator; this blog is kind of me-centric, but they are the masterminds of this whole business.)

We concluded our scouting mission a bit before sunset, having gotten some good experience with ice driving and ideas of how long it took to drive out, and headed back to base. Next post: our scientific adventures on Tuesday.

The lesson in sea ice safety was quite interesting, though. The basic goal of sea ice safety is, of course, to avoid falling through the sea ice into the 28F/-2C seawater below. Thus the procedure is more or less as follows (DISCLAIMER: I am not a professional sea ice safety trainer. Should you find yourself with occasion to drive over sea ice, please consult someone who knows what they’re doing, first!)

1. Look for cracks in the surface. These can be quite thin, or mostly covered with snow, but it’s usually possible to spot them if you stay alert.

2. Shovel the snow off of the sea ice in a channel extending a couple of feet from the crack. Note that there are several levels of sea ice in this particular crack. This happens because the sea ice that formed when the crack opened and re-froze hasn’t had a chance to get as thick as the older sea ice.

3. Drill some holes to check the ice thickness. The standard drill bit used for this is one meter long, so it doubles as a convenient measuring stick.

4. The ice must be at least 30″ thick to be considered safe. The edges of this crack are too far apart to drive over, and the central ice is too thin to drive on, so in this case we’ll have to find another place to cross.

If the crack is narrow enough, however–less than 1/3 of your tread length–then you can just drive over it.

(That’s my artistic rendering of a Pisten Bully.) As of Saturday morning, I know how to drive one. WHEE!)

You may recall from earlier posts how increased albedo can lead to a Snowball and CO2 can end one. As the planet cooled off and the climate system change, new types of ice could form that are rarely, if ever, found on our modern Earth. That’s why we’re down here in Antarctica in the winter–to find modern analogs of this very, very cold ice.

During our first couple of weeks here we’ll be looking for cold sea ice. “Sea ice” in science terms means ice that forms when seawater freezes–ice that formed from fresh water just happens to be floating on the sea, like icebergs, doesn’t count. When sea water begins to freeze, it forms a large number of small crystals of ice, called frazil. This stage is also called “grease ice” because it looks a bit like an oil slick on the water. Eventually the crystals begin freezing together into a solid sheet. As they freeze they trap small pockets of salt water, and these are what we’re really interested in.

As you may know, salt lowers the melting point of ice so that it becomes liquid at lower temperatures, a property that is useful when melting ice off of driveways or making ice cream by hand. Sea water averages about 3.5% salt (that’s six or seven teaspoons in a quart of salt for you American types, or 35g in a liter for the rest.) This particular salinity level means it freezes at 28F or -2C. As it freezes, the ice pushes out the salt, and the water in the pockets of salt water–the brine pores–gets saltier. If the ice gets colder, this saltier water will also start to freeze, pushing out more salt and making the brine pockets smaller and saltier still.

At -9F/-23C, some of the salt in the water starts to form crystals, called hydrohalite. Like the many small crystals in snow or table salt, these crystals of hydrohalite are good at scattering light. By sending light back out the way it came, the crystals in the brine pockets can increase the amount of light reflected from the sea ice. Our colleague Bonnie Light demonstrated this effect in the lab, and we are hoping to find it out in the field. These albedo measurements will help improve models of Snowball Earth. Because so much area in the sunlit tropics is covered in sea ice on Snowball Earth, small changes in albedo can have large effects, so it’s helpful to have measurements that are as accurate as possible.

Not all of our equipment is here or unpacked yet, but I’ll post photos when it is.